An inkjet recording apparatus that forms an image on a recording medium by ejecting ink from the nozzles of inkjet heads by utilizing the electromechanical conversion action of a piezoelectric element has been proposed. In an inkjet recording apparatus, if gas dissolved in ink becomes bubbles and remains in the ink, it causes a failure such as non-ejection of ink from the nozzles.
For this reason, one of the conventional inkjet recording apparatuses is known to include a degassing apparatus on an ink supply path for supplying ink from the ink tank to inkjet heads (International Publication WO2015/125521). This degassing apparatus has internal hollow fibers including gas permeable films.
The degassing apparatus is configured as an internal perfusion type in which ink is perfused through the hollow portion in the hollow fibers or an external perfusion type in which ink is perfused over the outer periphery of the hollow fibers. In the internal perfusion type degassing apparatus, the outer periphery of the hollow fibers is depressurized by a vacuum pump, whereas in the external perfusion type degassing apparatus, the air pressure in the hollow portion in the hollow fibers is reduced by a vacuum pump. Then, the dissolved gas in the ink permeates the hollow fibers and is removed from the ink.
In the degassing apparatus as described above, components in the ink may precipitate in the hollow interior of the hollow fibers, and the hollow interior may become clogged. Such clogging occurs, whether the degassing apparatus is an internal perfusion type or an external pefusion type. When the hollow interior of the hollow fibers is clogged, the flow of the liquid perfusing through the hollow interior is inhibited, or the flow of the dissolved gas that has permeated the hollow interior is inhibited, and the dissolved gas in the ink cannot be sufficiently removed. As a result, a failure such as non-ejection of ink occurs.
When a failure such as non-ejection of ink occurs, clogging of the hollow interior of the hollow fibers is suspected as the cause thereof. Therefore, the hollow fibers are replaced with new fibers. However, the cause of a failure such as non-ejection is not limited to clogging in hollow fibers. If the cause of a failure is not clogging in hollow fibers or if there is another cause of clogging in hollow fibers, the failure is not resolved just by the replacement of the hollow fibers. Therefore, the real cause of the failure needs to be found, which is cumbersome. In addition, the replacement of the hollow fibers conducted in this case might even be unnecessary, which could waste the material.